Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA.
RNA Biol. 2013 Apr;10(4):490-4. doi: 10.4161/rna.24085.
Transgenerational reprogramming of DNA methylation is important for transposon silencing and epigenetic inheritance. A stochastic regulation of methylation states in the germline may lead to epigenetic variation and the formation of epialleles that contribute to phenotypic variation. In Arabidopsis thaliana inbred lines, the frequency of single base variation of DNA methylation is much higher than genetic mutation and, interestingly, variable epialleles are pre-methylated in the male germline. However, these same alleles are targeted for demethylation in the pollen vegetative nucleus, by a mechanism that seems to contribute to the accumulation of small RNAs that reinforce transcriptional gene silencing in the gametes. These observations are paving the way toward understanding the extent of epigenetic reprogramming in higher plants, and the mechanisms regulating the stability of acquired epigenetic states across generations.
跨代 DNA 甲基化重编程对于转座子沉默和表观遗传遗传至关重要。生殖系中甲基化状态的随机调控可能导致表观变异和形成epialleles，从而导致表型变异。在拟南芥自交系中，DNA 甲基化单碱基变异的频率远高于基因突变，有趣的是，可变的 epialleles 在雄性生殖系中预先被甲基化。然而，在花粉营养核中，通过一种似乎有助于积累小 RNA 的机制，这些相同的等位基因被靶向去甲基化，从而增强配子中转录基因沉默。这些观察结果为理解高等植物中表观遗传重编程的程度以及调节跨代获得的表观遗传状态稳定性的机制铺平了道路。
